While muscle diseases include very many diseases, most of the symptoms thereof are muscle atrophy and muscle weakness associated therewith. The etiology of the muscle atrophy includes abnormality in the muscle itself and abnormality in the nerve that moves the muscle, where the former is called a muscle myogenic disease (myopathy), and the latter is called a neurogenic disease. The representative myopathy includes muscular dystrophy, muscular atrophy and the like. In Duchenne muscular dystrophy with the highest number of patients from among muscular dystrophies, one codon changes, by point mutation, to a stop codon meaning the termination of protein synthesis, due to which dystrophin protein is not synthesized. It is a disease developed only in boys by sex chromosome recessive inheritance, and said to be developed by 3 to 5 per 100,000 boys, and one per 2000-3000 newborn boys. There is not any good treatment method for muscular dystrophy, and the development of a treatment method has been desired. Miyoshi myopathy (MM) is one of the congenital distal myopathy (Miyoshi, K. et al. Brain 109 (Pt 1), 31-54, 1986), and caused by defective muscle membrane repair due to mutated Dysferlin (Liu, J. et al. Nat Genet. 20, 31-36, 1998, and Bansal, D., et al. Nature 423, 168-172, 2003).
For the development of a therapeutic drug, a model reflecting the human pathology in vitro is required. With the development of an induced pluripotent stem cell by reprogramming a somatic cell in recent years, utilization of a cell generated from patient's own cell as a pathology model is expected. While there are some reports on the method of inducing skeletal muscle cells from human pluripotent stem cells (Zheng, J. K. et al., Cell Res., 16: 713-22, 2006, Barberi, T. et al., Nat. Med., 13: 642-8, 2007), a method of efficiently inducing a cell in the number necessary for the development of a therapeutic drug has not been reported yet.
Directed differentiation by driving master transcriptional factor, MyoD1, from adult somatic cells was initially established for myogenic differentiation in 1988 (Tapscott, S. J., et al. Science 242, 405-411, 1988). Various types of cells can give rise to myocytes driven by forced expression of MyoD1 (Mizuno, H., et al. Plastic and reconstructive surgery 109, 199-209, 2002, and Gianakopoulos, P. J., et al. The Journal of biological chemistry 286, 2517-2525, 2011). In pluripotent stem cells, mouse embryonic stem cells can differentiate to myocytes by Tetracycline (Tet)-inducible MyoD1 expression (Ozasa, S., et al. Biochemical and biophysical research communications 357, 957-963, 2007), and hiPSC-derived fibroblasts can also differentiate to myocytes by MyoD1 mRNA treatment after differentiation under the condition without FGF for 4 weeks (Warren, L., et al. Cell stem cell 7, 618-630, 2010).